Double throw switch



Sept. 15, 1970 H. L. DBIKIN 3,529,101

I DOUBLE THROW SWITCH Filed May 9, 1968 n 2 Sheets-Sheet l Filedlaay 9',` 1968 Sept. l5, -1970 H. 1 DoBRxKlN 3,529,107

` DOUBLE THROW swIT 2 Sheets-Sheet 2 l lll s Ivg?,

United States Patent O Illinois v Filed May 9, 1968, Ser. No. 727,855 Int. Cl. H01h 35/40 U.S. Cl. 200-83 9 Claims ABSTRACT OF THE DISCLOSURE A double throw switch having a pair of spaced terminals, a flexible switch arm fulcrummed intermediate its ends and between said terminals, the switch arm carrying contact elements at its opposite ends and being urged about said fulcrum in one direction in response to fluid pressure and urged in an opposite direction by a spring.

SUMMARY OF THE INVENTION Within a housing, a diaphragm is responsive to fluid pressure entering the housing to move a motion-transmitting member which is in engagement with a flexible switch arm fulcrummed within the housing. The fulcrum for the switch arm is positioned between a pair of contact members within the housing, the switch arm carrying a contact element adjacent each of its ends. A yielding means engages the opposite surface of the switch arm in substantial alignment with the motion-transmitting member whereby the switch arm is moved in relation to its fulcrum in one direction in response to fluid pressure entering said housing and in the opposite direction in response to diminution of said fluid pressure and the action of said yielding means. The switch arm has a source of electrical energy connected thereto and is generally J-formed in planar configuration to provide for the desired movement of the arm portions on opposite sides of said fulcrum, while retaining the switch arm within a circular housing of minimum dimension and accommodating a 90 circumferential spacing of terminals.

This invention relates to switches, and has particular relation to switches employable in connection with fluid pressure brake systems for vehicles.

One purpose of the invention is to provide a stop light switch responsive to predetermined uid pressure in a vehicle brake system for rapid and positive illumination of the stop light signal indicating a brakes-on condition.

Another purpose is to provide a double throw, pressure-responsive switch of maximum simplicity having a switch arm fulcrummed intermediate its ends and carrying contact elements adjacent its ends for alternate engagement with spaced contact members.

Another purpose is to provide a pressure-responsive stop light switch insuring a means for passage of electrical energy therethrough at all times.

Another purpose is to provide a double throw, fluid pressure-responsive switch of maximum simplicity and minimum cost in manufacture, while providing for an extended useful life thereof.

Other purposes may appear from time to time during the course of the specification and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention illustrated more or less diagrammatcally in the accompanying drawings wherein:

FIG. l is a side view with parts in cross section and moved slightly for clarity;

FIG. 2 is a top view, taken substantially on a line 2-2 of FIG. l and with parts broken away;

FIG. 3 is a detail view of one form of the invention;

3,529,107 Patented Sept. 15, 1970 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, the numeral 1 generally designates a housing formed of cover part 1a and base part 1b. A fitting 2 carried by housing part 1b defines a fluid pressure entry passage 3 positioned to deliver fluid pressure to one side 4 of a diaphragm 5. The opposite side 7 of diaphragm 5 engages a spherical end surface 8 of a motion-transmitting member 9. An internal housing part 10 has a generally centrally positioned aperture 11 through which an extension 12, having a generally rounded or spherical end surface, extends. Housing part 10 carries an upstanding fulcrum portion 15 extending into a switch arm chamber 16.

Within chamber 16 a flexible switch arm 17 of electrical energy-transmitting material extends. As may be best seen in FIG. 2, the arm 17 -generally takes the form of a .l in planar configuration to provide for its reception within a generally circular housing 1 of minimum diameter and to produce the action desired as described below. Intermediate its ends the switch arm 17 is downwardly offset as indicated at 18. Within the offset area 18 the switch arm is upwardly struck or offset, as indicated at 19. The upset portions 18 and 19 provide a seat for fulcrum 15. A linger 20 depends from housing cover part '1a and contacts the upper surface, as the parts are shown, of upset 19 in alignment with fulcrum 15.

Adjacent its opposite ends, the arm 17 carries upwardly disposed contact elements 25, 26. As the parts are shown, the elements 25 and 26 are carried on the upper surface of arm 17. A yielding means, such as the spring 27, is received within housing part 1a on the opposite side of chamber 16 from member 9. Spring 27 urges a motiontransmitting member 28 having a curved or spherical end surface similar to that of extension 12, against said upper surface of arm 17 in substantially axial alignment with extension 12. Means 29 preferably engages housing part 1a for adjustment of the effect of spring 27.

Positi-oned within chamber 16 and in vertical alignment, as the parts are shown, with contact element 25 is a contact member 30. Terminal post 31 is secured to member 30 and extends upwardly out of housing 1. Similarly, a contact member 35 is positioned in chamber 16 in substantially vertical alignment with contact element 26 and terminal post 36 is secured to contact member 35 and extends upwardly out of housing 1. A terminal post 37 extends from a point externally of housing 1 to a position within housing 1 from whence an electrical conductor, such as the wire indicated for example at 40 in FIG. 2, extends, the wire 40 being secured to arm 17 as indicated for example 41.

FIGS. 3, 4 and 5 illustrate the employment of an arm 17a of flexible material positioned, as seen in FIG. 3, so as to engage contact elements 25 and 26 with contact members 30, 35 when arm 17a is in its free state. FIG. 4 illustrates the condition when iluid pressure at a predetermined safe level is delivered to diaphragm 5 through inlet 3. FIG. 5 illustrates the condition when fluid pressure is absent from or below a safe level at inlet 3.

Whereas there has been shown and described an operative form of the invention, it should be understood that this showing and description are to be taken in an illustrative or diagrammatic sense only. There are many modications in and to the invention which will be apparent to those skilled in the art and which will fall within the scope and spiri-t of the invention.

'Ille use and operation of the invention are as follows:

With iluid pressure in the emergency brake system of the vehicle, said fluid pressure will be present at inlet 3 and if said fluid pressure be at the safe predetermined level, the diaphragm will be urged inwardly of hou-sing 1 as will member 9 to move switch arm 17 about or on its fulcrum 15. The movement of arm 17 on fulcrum 15 produces an upward movement of contact element 26, as the parts are shown in FIG. '1, a corresponding downward movement of contact element 25 to provide for engagement of element 26 with contact member 35 and a separation of contact element 25 from contact member 30. It will be understood that contact member 35 is incorporated with the normal electrical system provided for normal service brake operation and that engagement of element 26 with con-tact member 35 will insure delivery of electrical energy through a service system stop light switch for illumination of a stop light, for example, in response to normal brake operation through said service system.

Should, however, there occur a leak or break in the emergency air brake system, the resulting diminution of fluid pressure in said system will als-o occur at inlet 3 and spring 27 will move member 1-2, arm 17, member 9 and diaphragm 5 into the position shown in FIG. 1, the ar-m 17 being moved in the opposite direction from that occurring when uid pressure is delivered at inlet 3 above a predetermined level. With the parts as shown in FIG. 1, contact element 26 is fully separated from contact member 35 and contact member 25 is in engagement with member 30. Electrical energy thus delivered by terminal 37, wire 40 and connection 41 to the arm 17 is delivered through the contact element 25 and contact member 30 to the post 31 and thus to the stop light (not shown) for illumination thereof.

With the arrangement of FIG. l, a momentary null position is possible in which arm 17, dur-ing its excursion from a position wherein element -26 engages member 35 and element 25 is separated from member 30 to a posi-tion in which element 26 and member 35 are separated and element 25 engages member 30. In such position, a vehicle stop light would not be illuminated even though the operator was applying service system brakes or the automatic emergency brake application was occurring. While such position would be occupied only momentarily, it is eliminated in the arrangement of FIGS. 35, wherein an arm 17a is formed of exible, springlike material and positioned to engage elements 25 and 26 with members 30 and 35, respectively. Pressure delivered to diaphragm 5 deforms or flexes the portion of arm 17a to the right of fulcrum 15, as the parts are shown, to maintain engagement of ele-ment 26 with member 35 and to deflect or spring the left-hand portion of arm 17a downwardly to separate element 25 from member 30. Similarly, spring 27, with diminished pressure at inlet 3, bows or deflects the right-hand portion of arm 17a downwardly to separate element 26 from member 35. It will be realized that the left-hand portion of arm 17a will snap element 25 into engagement with member 30 immediately upon downward movement of extension 12 to illuminate a stop light upon application of emergency brakes.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A double throw switch including a housing, a culcrum in said housing, a switch arm of springlike material and having an intermediate portion seated on said fulcrum, a Contact member on each side of said fulcrum, a contact element carried adjacent each of the opposite ends of said arm, a diaphragm in said housing, a fluid pressure inlet positioned in said housing for delivery of fluid pressure to one side of said diaphragm, a motion-transmitting member engaging the opposite side of sai-d diaphragm, said motion-transmitting member having a portion engaging one surface of said arm at one side of said fulcrum, a yielding means engaging the opposite surface of said arm on said Iside of said fulcrum, an electrical energy conductor connected to said arm, and offset portions positiond on said arrn intermediate its ends, said oifset portions being and defining a fulcrum seat therewithin.

2. The structure of claim 1 wherein said yielding means includes a spring, a motion-transmitting member slidable in said housing and urged against said opposite surf-ace of said arm by said spring, said rst and second motion-transmitting members being in substantially axial alignment.

3. The structure of claim 1 characterized by and including a nger extension formed in said housing and engaging said opposite surface of said arm in substantial alignment with said fulcrum,

4. The structure of claim 3 wherein said fulcrum and said linger extension are formed of insulating material.

5. The structure of claim 1 wherein said switch arm is generally I -shaped in planar configuration, said fulcrum engages said arm adjacent the joinder of the straight and curved portions of said configuration and said motion- 4transmitting member engages said s-traight portion of said contiguration adjacent the point of said fulcrum engagement.

6. The structure of claim 1 wherein said switch arm is formed or relatively thin springlike material and positioned to engage said contact elements with said contact members when said arm is in its free state, said arm being deformed in one direction in response to delivery of uid pressure to said diaphragm to deflect one of said elements out of engagement with one of said members, said arm being deformed in an opposite direction in response to diminution of said uid pressure to separate the other of said elements from the other of said members and to permit immediate re-engagement of said one element with said one member.

7. The structure of claim 6 wherein said arm is deformed in said one and said opposite directions on one side of said fulcrum.

8. The structure of claim 6 wherein said arm is I- shaped in planar configuration, said fulcrum engages said arm adjacent the joinder of the straight and curved portions of said configuration and said straight portion is deformed in said one and said opposite directions.

9. The structure of claim 8 wherein said one element is carried adjacent the distal end of the curved portion of said configuration.

References Cited UNITED STATES PATENTS 1,475,313 11/192'3 Newhard. 3,321,594 5/1967 Reise et al 20G-83 XR 3,365,557 l/-19\68 Cooper et al. 200-8'3 3,436,503 4/ 1969 Moody 200-83 lROBERT K. SCHAEFER, Primary Examiner J. R. SCOTT, Assistant Examiner 

